Medical probe with fluid rotary joint

ABSTRACT

A catheter is provided that includes an external sheath, a rotatable conduit housed within the external sheath, and a fluid rotary joint having a rotatable insert that places an inner lumen of the rotatable conduit in fluid communication with an external port under rotation of the rotatable conduit. The rotatable insert may include a channel structure including an external annular channel. The rotatable conduit is received within the channel structure such that the inner lumen is in fluid communication with the external port through the annular channel under rotation. The external sheath may define an outer lumen that may be in fluid communication with the inner lumen at a location remote from a proximal portion of the catheter, and the outer lumen may be in fluid communication with a secondary port. The rotatable conduit may be housed within a torque cable that is connected to the rotatable insert.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/490,930, titled “CATHETER WITH FLUID ROTARY JOINT” and filed on May27, 2011, the entire contents of which are incorporated herein byreference.

BACKGROUND

The present disclosure relates to medical probes, and more particularly,the present disclosure relates to medical probes, such as catheters, inwhich a fluid is transported within a portion of the probe.

Medical probes, such as catheters, are commonly used in minimallyinvasive procedures for the diagnosis and treatment of medicalconditions. Such procedures may involve the use of intraluminal,intracavity, intravascular, and intracardiac catheters and relatedsystems. When performing such procedures, imaging and treatmentcatheters are often inserted percutaneously into the body and into anaccessible vessel of the vascular system at a site remote from thevessel or organ to be diagnosed and/or treated. The catheter is thenadvanced through the vessels of the vascular system to the region of thebody to be treated.

The catheter may be equipped with an imaging device employing an imagingmodality such as optical imaging, optical spectroscopy, fluorescence,infrared cardiac endoscopy, acoustic imaging, photo-acoustic imaging,thermography, and magnetic resonance imaging. For example, an ultrasoundor optical imaging device may be employed to locate and diagnose adiseased portion of the body, such as, a stenosed region of an artery.The catheter may also be provided with a therapeutic device, such asthose used for performing interventional techniques including balloonangioplasty, laser ablation, rotational atherectomy, directionalatherectomy and the like.

Imaging catheters, such as intravascular and intracardiac ultrasoundcatheters, typically require the catheter body to be purged of airduring operation. The purging is performed to support the efficientpropagation, within the catheter body, of imaging energy generated ordetected by one or more internal transducers. For example, an ultrasoundtransducer housed within an intravascular ultrasound catheter istypically immersed in a liquid during operation to support the efficientcoupling of acoustic waves from the transducer to the external medium tobe imaged.

The fluid is commonly introduced into the catheter by a procedurereferred to as “flushing” the catheter, where fluid is injected into thecatheter via a port at the proximal end. This fluid, which is typicallya liquid such as saline or sterile water, travels along the length ofthe inner main lumen of the catheter and purges air out of a port nearthe distal tip of the catheter. Other catheters do not support flushingof the catheter through ports available outside the body. Such catheterstypically require manual injection of a fluid coupling medium to thedistal tip of the catheter via a needle attached to a syringe. It isdesirable to making flushing a safe, simple, quick and effectiveprocedure. In many applications, it is also desirable to fluidly isolateinner portions of catheters from the anatomic environment into whichthey are used. Generally, the catheter is flushed with liquid prior toinsertion of the catheter into the vasculature if the physician wishesto minimize the probability of introducing air bubbles into thebloodstream.

Many intravascular imaging catheters are designed such that, during use,blood can enter the catheter via the distal flushing port. This bloodcan interfere with the mechanical or imaging performance of thecatheter. For example, if the blood were to form a thrombus within theimaging catheter, it could damage delicate components within thecatheter and/or be expelled during a subsequent flushing procedure,potentially leading to embolic complications. Furthermore, the use of adistal flushing port that potentially releases particles or solublematerials from inside the catheter into the vasculature reduces designflexibility with respect to the selection of materials used within thecatheter. It also requires that the fluid used for flushing bephysiologically compatible, such as saline.

In some cases, a catheter may be inadequately flushed, and the resultingimaging quality can be significantly degraded. For example, air bubbleson ultrasound transducers or optical components substantially reduceimage quality if they lie within regions in which acoustic waves oroptical energy travel.

As an alternative to flushing via a proximal port and allowing fluid toexit via a distal port, some catheters have been designed with aseparate lumen as part of the imaging catheter to deliver fluid to thedistal end of the catheter, allowing the fluid to “backfill” the mainlumen of the catheter. Alternatively, the separate lumen can used as aventing lumen, where the fluid is introduced via the main lumen, and theseparate lumen allows air to escape.

The separate flushing lumen takes up space and is often made as small aspossible to avoid an excessive increase in the diameter of the catheter.This can unfortunately be a significant limitation in the case ofintravascular catheters, which typically require a compact configurationin order to enable delivery into the vasculature. For example, catheterscurrently employed for intravascular ultrasound and intracardiacechocardiography are approximately 0.8 to 4 mm in diameter, where thesmaller sizes of probes can be delivered more distally within thevascular tree of the coronary anatomy as the vessel caliber tapers downor as diseased vessels are stenosed. Furthermore, such probes may beadvanced across the atrial septum from the right atrium into the leftatrium of the heart via either a pre-existing communication, such as apatent foramen ovale, or via a communication created during a procedure,such as a trans-septal puncture. Smaller sizes generally allow forinterrogation of a larger portion of the coronary or cardiac anatomy ormay allow for the creation of smaller holes through which to access thedesired anatomic regions. It is therefore desirable for a probe and itscomponents to be contained within a minimal outer diameter or minimalcross-sectional area to enable imaging.

SUMMARY

Embodiments herein provide a catheter including an external sheath, arotatable conduit housed within the external sheath, and a fluid rotaryjoint having a rotatable insert that places an inner lumen of therotatable conduit in fluid communication with an external port underrotation of the rotatable conduit. The rotatable insert is rotatablysupported within an outer housing and may include a channel structureincluding an external annular channel. The rotatable conduit is receivedwithin a longitudinal portion of the channel structure such that theinner lumen is in fluid communication with the external port through theannular channel under rotation of the rotatable conduit. The externalsheath may define an outer lumen that may be in fluid communication withthe inner lumen at a location remote from a proximal portion of thecatheter, and the outer lumen may be in fluid communication with asecondary port. The rotatable conduit may be housed within a torquecable that is connected to the rotatable insert.

Accordingly, in a first aspect, there is provided a medical probecomprising: an external sheath; a rotatable fluid conduit housed withinthe external sheath, the rotatable fluid conduit including an innerlumen; and a fluid rotary joint comprising: an outer housing includingan external port, wherein the external sheath is connected to the outerhousing; a rotatable insert having an inner channel, wherein therotatable insert is rotatable within the outer housing, and wherein aproximal portion of the rotatable fluid conduit is received within theinner channel of the rotatable insert, such that the inner channel is influid communication with the inner lumen; wherein the inner channel isin fluid communication with the external port under rotation of therotatable fluid conduit; and wherein the rotatable insert is connectableto an external rotational drive mechanism.

In another embodiment, there is provided a fluid rotary joint for usewith a medical probe, the medical probe including an external sheathhousing a rotatable fluid conduit, the rotatable fluid conduit having aninner lumen, the fluid rotary joint comprising: an outer housingincluding an external port, wherein the outer housing is connectable tothe external sheath of the medical probe; a rotatable insert includingan inner channel, wherein the rotatable insert is rotatable within theouter housing, and wherein the inner channel of the rotatable insert isconfigured to receive a proximal portion of the rotatable fluid conduit,such that the inner channel is in fluid communication with the innerlumen; wherein the inner channel is in fluid communication with theexternal port under rotation of the rotatable fluid conduit; and whereinthe rotatable insert is connectable to an external rotational drivemechanism.

A further understanding of the functional and advantageous aspects ofthe disclosure can be realized by reference to the following detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure will now be described, by way of exampleonly, with reference to the drawings, in which:

FIG. 1a shows a catheter system employing a fluid rotary joint toprovide a working fluid to an inner lumen of the catheter.

FIG. 1b illustrates the interfacing of the rotary and non-rotarycomponents of the system.

FIG. 1c shows an alternate embodiment of a fluid rotary joint where thesecondary port is positioned in a location other than on the proximalconnector.

FIG. 1d shows a fluid rotary joint that is controlled by an externalpump.

FIG. 2 shows cross sectional views across section A-A in FIG. 1, inwhich (a) shows a coaxial embodiment, (b) shows an off-axis embodimentand (c) shows a coaxial embodiment with the flushing conduit integratedclosely with a torque cable.

FIG. 3a provides a cross-sectional view through a fluid rotary joint,showing the outer housing and rotatable insert.

FIG. 3b shows a close-up view of region C in FIG. 3 a.

FIG. 3c shows a cross-section through line B-B in FIG. 3(a), showing anexample configuration of the lateral and annular channels.

FIG. 3d shows an alternative cross-section through line B-B in FIG. 3(a)using non-radial lateral channels

FIG. 3e shows a cutaway view of the embodiment of FIGS. 3a-c where theannular channel is formed within the rotary insert

FIG. 3f illustrates a cutaway view of an alternative embodiment in whichthe annular channel is formed within the outer housing.

FIG. 3g provides a cross-sectional view through another embodiment of afluid rotary joint where the active conduit contains an optical channel.

FIG. 3h provides a cross-sectional view through an embodiment of a fluidrotary joint in which the active conduit includes both optical andelectrical channels.

FIG. 4 shows the outer housing of the fluid rotary joint in which (a)shows a perspective view and (b) shows an exploded longitudinalcross-sectional view.

FIG. 5 provides cross-sectional views of various embodiments of a distalend of a catheter comprising an inner fluid lumen, where (a) shows fluidflowing over an ultrasonic transducer, (b) shows an embodiment in whichthe working fluid flows around an ultrasonic transducer, (c)-(e) showviews of an embodiment in which the working fluid is deflected prior toencountering an ultrasonic transducer, (f) shows the fluid exiting via adistal exit port, (g) shows an alternative direction of fluid transportas compared to that shown in (a), (h) shows the use of a fluid rotaryjoint in a thermal application where fluid enters a network of channelsdistributed around a mechanical tool for cooling or heating the tool and(i) shows the use of a balloon catheter employing the fluid rotaryjoint.

FIG. 6 shows a system level diagram illustrating various components ofthe catheter system.

DETAILED DESCRIPTION

Various embodiments and aspects of the disclosure will be described withreference to details discussed below. The following description anddrawings are illustrative of the disclosure and are not to be construedas limiting the disclosure. Numerous specific details are described toprovide a thorough understanding of various embodiments of the presentdisclosure. However, in certain instances, well-known or conventionaldetails are not described in order to provide a concise discussion ofembodiments of the present disclosure.

As used herein, the terms, “comprises” and “comprising” are to beconstrued as being inclusive and open ended, and not exclusive.Specifically, when used in the specification and claims, the terms,“comprises” and “comprising” and variations thereof mean the specifiedfeatures, steps or components are included. These terms are not to beinterpreted to exclude the presence of other features, steps orcomponents.

As used herein, the term “exemplary” means “serving as an example,instance, or illustration,” and should not be construed as preferred oradvantageous over other configurations disclosed herein.

As used herein, the terms “about” and “approximately”, when used inconjunction with ranges of dimensions of particles, compositions ofmixtures or other physical properties or characteristics, are meant tocover slight variations that may exist in the upper and lower limits ofthe ranges of dimensions so as to not exclude embodiments where onaverage most of the dimensions are satisfied but where statisticallydimensions may exist outside this region. It is not the intention toexclude embodiments such as these from the present disclosure.

Embodiments disclosed below provide a catheter with a rotatable fluidconduit having an inner lumen that is in fluid communication at itsproximal end with a fluid rotary joint. Embodiments described belowenable transport of a working fluid through the rotatable inner lumen,thus providing advantages and benefits related to system size,performance, compatibility and flexibility.

Referring to FIGS. 1 and 2(a), catheter 100 is shown having an externalsheath 105. External sheath 105 is a hollow, elongate shaft made ofphysiologically compatible material and having a diameter suitable topermit insertion of the hollow elongate shaft into bodily lumens andcavities. External sheath 105 may be flexible, or may be rigid forapplications where a rigid imaging probe may be desired, such as forsome bronchoscopic, laryngoscopic or otoscopic applications.

Catheter 100 includes proximal connector 200 at its proximal end.Proximal connector 200 comprises a fluid rotary joint including outerhousing 210 and a rotatable insert 215 (shown in FIG. 3a and FIG. 3b ).Proximal connector 200 is also connectable to a patient interface module536, which couples other external rotatable and non-rotatable componentsto rotating and non-rotating components of catheter 100. Patientinterface module 536 may have one or more cables 535 that receive powerand enable communication with a console, such as an image processing anddisplay system. Although the fluid rotary joint is shown the presentexample implementations as being provided at a proximal end of catheter100, it is to be understood that any component along the length of therotating components of catheter system 560 may contain the fluid rotaryjoint.

For clarity, “rotatable” or “rotating” components refer to componentsthat rotate with a rotatable shaft. An example of a rotatable componentis a torque cable (described and shown below), at least a portion ofwhich lies within an external sheath of catheter 100 and is able torotate independent of the external sheath. “Non-rotating” componentsrefer to components that do not rotate with the rotatable shaft, but maynonetheless be rotated, such as under manual manipulation of thecatheter's outer housing or external sheath.

FIG. 2(a) shows a cross-section as indicated at section A-A in FIG. 1a .Torque cable 120 is disposed within external sheath 105 for rotating afluid conduit 110 and may contain one or more optical and/or electricalchannels housed within active conduit 125. Such torque cables aretypically formed from strands of wires arranged in various manners (forexample, as taught by Crowley et al. in U.S. Pat. No. 4,951,677, titled“Acoustic Imaging Catheter and the Like”), but can also include tubing,such as hypotubing made of stainless steel or nitinol. Torque cables canalso be substituted with rotatable conduits formed from materials suchas polymeric tubing, such as those made of polyimide or PEEK. Torquecables can also be made with different configurations along theirlength, such as a hypotube construction along a proximal extent andstrands of braided or coiled wires along a distal extent.

In some embodiments, the outer catheter diameter is in the range ofapproximately 0.8 to 4 mm. Also, in some embodiments, the length of thecatheter portion is approximately 5 to 150 cm in length. Although suchsizes are typical sizes for imaging catheters, it is to be understoodthat other sizes may be suitable for other applications involvingmedical probes.

Fluid conduit 110 houses inner lumen 115 and may, in some embodiments,be made from liquid impermeable materials such as, but not limited to,PEEK, nylon, polyimide, PEBAX, PTFE, stainless steel, and nitinol. Fluidconduit 110 may be impermeable to liquids along all or most of itslongitudinal extent. Fluid conduit 110 and torque cable 120 arerotatable and rotate in unison under the application of an externaltorque to torque cable 120, as further described below. If present, oneor more active conduits 125 within torque cable 120 would also rotate inunison with torque cable 120.

A diagnostic or therapeutic assembly, such as an imaging assemblycomprising an imaging transducer, or a treatment device such as a laserablation emitter, may be connected to active conduit 125, at a locationremote from the proximal end of catheter 100, for the transmission ofpower, imaging energy, and/or received signals. At least a portion ofthe diagnostic or therapeutic assembly rotates in unison with torquecable 120. In the case where active conduit 125 contains one or moreelectrical channels, active conduit 125 may be electrically insulatedfrom working fluid contained within catheter 100.

Catheter 100 further includes non-rotating outer lumen 130, which may bein fluid communication with inner lumen 115 at a location remote from aproximal end of fluid conduit 110. In some embodiments, outer lumen 130is fluidly isolated from its surrounding environment within thevasculature. Optionally, as shown in FIG. 5f , outer lumen 130 may exitcatheter 100 at one or more locations, for example, at distal flush port135 at a distal portion 140 of catheter sheath 105.

Referring again to FIG. 1a , at proximal end 150, catheter 100 isreceived by proximal connector 200. The fluid rotary joint, which ishoused within proximal connector 200, provides fluid communication ofinner lumen 115 with non-rotating fluid port 205 during rotation oftorque cable 120 and fluid conduit 110. For example purposes, the fluidrotary joint and fluid port 205 are illustrated as incorporated intoproximal connector 200.

As shown in FIG. 1(b), patient interface module 536 performs, in part,as a rotational adapter that mechanically supports non-rotatingcomponents, rotationally drives rotatable components, and couples otherrotating components of the system to signal processing subsystems andother subsystems (such as those shown in FIG. 6). Patient interfacemodule 536 may also include a rotational drive mechanism, whereby acontrollable motor is mechanically coupled to a rotatable portion 537(shown in FIG. 1) of patient interface module 536. Such mechanicalcoupling between rotatable portion 537 of patient interface module 536and controllable motor (not shown) may be provided by belts, pulleys,gears and other coupling mechanisms known to those skilled in the art.Alternatively, rotatable portion 537 may be directly coupled to a hollowbore shaft of a controllable motor. Furthermore, as shown in FIG. 1a andFIG. 4a (described further below), outer housing may include a latchingmechanism 330 for securing the fluid rotary joint to a patient interfacemodule, as described below.

Electrical and/or optical channels within active conduit 125 (such as acoaxial electrical cable or optical fiber) are directly or indirectlyfed through the fluid rotary joint and are coupled, through patientinterface module 536, to back-end subsystems. Accordingly, patientinterface module 536 facilitates transmission of signals within anyfibers and/or wires to the appropriate subsystems.

Referring to FIG. 1(b), the adapter can include slip rings, opticalrotary joints and other such implements for electrically or opticallycoupling a rotary component to a non-rotary component in the rest of thesystem and to enable communication of necessary electrical and opticalsignals with the rest of the system. A conductor mounted onto a rotatingcomponent in catheter 100 can be coupled to non-rotating conductingelements via metallic slip rings and springs, metallic slip rings andbrushes or other commonly known methods of forming conductive contactbetween a stationary conductor and a rotary conductor.

In some embodiments, active channel 125 may additionally oralternatively include a fiber optic that is in optical communicationwith one or more optical components provided in an imaging assembly,where the imaging assembly may be connected to torque cable 120.Examples of suitable optical components include a lens, alight-deflecting element, and an optical spacer. As shown in FIG. 1(a),the catheter optionally includes guidewire 180, shown in a “rapidexchange” configuration, where guidewire 180 enters catheter externalsheath 105 at first guidewire port 185, and exits catheter 100 at secondguidewire port 190. It is to be understood that guidewire mayalternatively be employed in an “over the wire” configuration.

FIG. 1(a) also illustrates an example embodiment in which proximalconnector 200 also includes a non-rotating secondary fluid port 320. Asfurther described below, secondary port 320 may be in fluidcommunication with an outer, non-rotating lumen of catheter 100, wherethe outer lumen is in fluid communication with the inner lumen at alocation within catheter 100 that is remote from proximal end ofcatheter 100, thereby forming a closed internal fluid path connectingport 205 with secondary port 320.

FIGS. 1(c) and 1(d) illustrate two alternative embodiments of thecatheter system. In FIG. 1(c), an example embodiment is shown in whichsecondary port 320 is located along the external sheath, at a locationthat is remote from the proximal end of catheter 100.

FIG. 1(d) illustrates an embodiment in which a pump mechanism 550 isshown for circulating a fluid between port 205 and secondary port 320with flow channels 552 and 554. Pump mechanism may be any suitable typeof pump, such as, for example, peristaltic, centrifugal or diaphragmpumps. Alternatively, a non-recirculating pump may be used, and channel554 may be directed to a waste container.

FIG. 2(b) illustrates another embodiment of the catheter cross section(section A-A) in which fluid conduit 110 and active conduit 125 areseparately housed within torque cable 120, where fluid conduit 110functions as a dedicated flow channel that does not house active conduit125.

Although outer lumen 130 is shown in FIGS. 2(a) and (b) to lie betweentorque cable 120 and external sheath 105, it is to be understood thatouter lumen 130 may also be in fluid communication with the regionbetween torque cable 120 and fluid conduit 110. For example, torquecables are often highly permeable to fluids, enabling the flow ofworking fluid through the wall of torque cable 120.

Alternatively, torque cable 120 may be made less permeable orimpermeable to the working fluid, for example by either by coating orotherwise integrating a liquid impermeable material such as a polymerwith the wall of the torque cable. Such an embodiment is illustrated inFIG. 2(c), where torque cable 120 is directly lined with fluid conduit110 as a lining on the inner surface of the torque cable. Alternatively,the lining can be on the outside of the torque cable, embedded withinthe torque cable or a combination thereof.

Although many of the embodiments disclosed herein include a torque cablefor providing rotary motion to an assembly or device remote from aproximal end of catheter 100, it is to be understood that any suitableshaft, tube or rotary conduit may be included. In some embodiments, therotary conduit providing rotary motion to the remote assembly or device,and the inner conduit may be one in the same. For example, in someimplementations, torque cable 120 may be impermeable, or may besubstituted with an impenetrable rotatable conduit (such as a hypotubecomponent), whereby the torque cable or rotary conduit may also act asfluid conduit 110.

Catheter 100 may include features (such as an external sheath comprisingtwo or more telescoping segments) that allow rotating components, suchas torque cable 120 and fluid conduit 110, to translate longitudinallyin unison within external sheath 105. This translational capability iscommonly referred to as “pullback” capability. In such an embodimentcomprising telescoping segments of the external sheath, the telescopingsegments may have a tight seal between each other, such as by beingconstructing with tight tolerances between the two parts or by inclusionof one or more o-rings, viscous fluids or similar sealing components.

FIGS. 3(a) and 3(b) illustrate an embodiment of fluid rotary joint 160that is configured for transporting working fluid through non-rotatingprimary port 205 and into rotatable inner lumen 115 of catheter 100, asshown by flow path 207 in FIG. 3(b). Fluid rotary joint 160 includesnon-rotating outer housing 210 (also shown in FIG. 4(a)) and rotatableinsert 215 that rotates within housing 210. As shown in FIG. 3(b), whichprovides a detailed view of the region marked “C” in FIG. 3(a), aproximal portion of rotatable conduit 110 is received within rotatableinsert 215 such that inner lumen 115 is in fluid communication withprimary port 205 under rotation of rotatable conduit 110.

As shown in FIGS. 3(a)-(d), primary port 205, annular flow channel 260,lateral flow channel 265 and longitudinal flow channel 270, which formchambers of fluid rotary joint 160, are in fluid communication withinner lumen 115 of fluid conduit 110. A fluid seal between the radiallyoutermost extent of rotatable insert 215 and the inner surface of outerhousing 210 is provided by distal seal 225 and proximal seal 230 (suchas o-rings) that are housed within seal appropriately sized recesseswithin rotatable insert 215. Distal seal 225 and distal seal insert 275(described in further detail below) prevent fluid within the chambers offluid rotary joint 160 from being in direct fluid communication withouter lumen 130 of catheter 100, with the exception of the fluid pathprovided by inner lumen 115 at a distal portion of catheter 100.

The rotatable insert 215 may, in some embodiments, have a size rangingfrom approximately 3 to 10 mm in outer diameter and 20 to 50 mm inlength.

FIGS. 3(c)-3(d) illustrate various example embodiments of thecross-sectional configuration of the fluid rotary joint along line B-Bof FIG. 3(a). While two lateral flow channels are shown in FIG. 3a , anynumber of radial flow channels between longitudinal flow channel 270 andannular flow channel 260 may be included. When two or more radial flowchannels are implemented, they may be uniformly distributed around thecircumference of annular flow channel to minimize vibrations.Furthermore, while FIG. 3(c) illustrates an embodiment in which lateralflow channels 265 are radial flow channels, it is to be understood thatthe lateral flow channels need not be radial in shape, and can beprovided with a non-radial geometry, for example, as illustrated bychannels 267 in FIG. 3(d).

FIGS. 3(e) and 3(f) show cut-away views illustrating optionalconfigurations of the annular channel. In FIG. 3(e), annular channel 260is shown as being formed within rotatable insert 215. An alternativeembodiment is shown in FIG. 3(f), where annular channel 261 is shown asbeing formed within outer housing 210. In other embodiments, the annularchannel may be formed in both rotatable insert 215 and in outer housing210.

In one embodiment, rotatable insert 215 is rotationally supported byrotatable shaft 537 of patient interface module (or of a suitablerotational drive mechanism). Rotatable insert 215 may be longitudinallyretained within outer housing 210 by retaining screw 220, which may abutagainst collar 219 and prevent rotatable insert 215 from translating ina longitudinal direction. Rotatable insert 215 may alternatively oradditionally be rotatably supported by a bearing (such as, for example,a Teflon™ bearing). This bearing may exist in the proximal connector 200or an interfacing component.

As further described below, distal seal 225 may be a partial seal, sothat fluid within chambers of fluid rotary joint 160 is in fluidcommunication with both inner lumen 115 and outer lumen 130 of catheter100, but whereby the distal seal 225 increases the resistance to flowbetween the chambers of fluid rotary joint 160 and outer lumen 130 ofthe catheter. Such a distal seal with a partial seal may be desirablefor embodiments similar to that shown in FIG. 5f . Proximal seal 230contributes to preventing fluid from leaking from fluid-filled chambersof the catheter 100 and proximal connector 200 out of the proximalextent 296 of proximal connector 200.

The inclusion of distal seal 225 increases (e.g. doubles) the runningfriction, because there are two seals instead of only the one proximalseal 230. This increase in friction can cause an undesirable heatgeneration, leading to temperatures that may be potentially unsafe tothe user or destructive to other components. Three factors fordecreasing the running friction are: rotational speed, seal diameter,and seal compression. The rotational speed may be determined by themedical probe functionality, and may be reduced in some applications inorder to generate less heat while still providing a suitable rotationrate. The diameters of proximal seal 230 and distal seal 225, however,can be kept small to reduce heat generation and be designed with minimalpre-compression force. To minimize temperature rise, the fluid rotaryjoint can be adapted to dissipate the generated heat to the ambient airquickly. For example, the walls of outer housing 210 can be kept thin,and, if possible, be made of a thermally conductive material, such asaluminum. It may be beneficial to include external features on the outerhousing for dissipating internally generated heat. These features mayinclude heat sinking fins and other known heat sinking structures.

As shown in FIGS. 3(a) and 3(b), secondary port 320 may be attached to,or formed within, a non-rotating component, such as non-rotating outerhousing 210 of proximal connector 200, thereby forming a closed internalfluid path to and from a distal region of catheter 100. Secondary port320 may optionally be a Luer connector of opposite gender to that ofprimary port 205. Alternatively, optional distal flush port 135, shownin FIG. 5f , may act as a substitute for secondary port 320. Asdescribed further in FIGS. 5(a)-(i), working fluid flowing within innerlumen 115 may be brought into fluid communication with outer lumen 130in a region of catheter 100 that is remote to the proximal end ofcatheter 100.

As further illustrated in FIGS. 3(a) and 3(b), rotatable insert 215 maybe connected to a proximal end of torque cable 120 by a fastener orclamping mechanism, such as set screw 245. Accordingly, the rotation ofrotatable insert 215 is coupled to torque cable 120, which in turnrotates the rotating components of catheter 100 housed within externalsheath 105.

As described above, rotatable insert 215 is further connectable at itsproximal end 295 to a rotatable drive assembly for imparting andcontrolling rotation to the rotating components of catheter 100 housedwithin or connected to torque cable 120. The rotatable drive assemblymay be provided within patient interface module 536, as noted above.

With further reference to FIGS. 3(a) and 3(b), working fluid transportedthrough primary port 205 in outer housing 210 is in fluid communicationwith annular flow channel 260 provided in rotatable inset 215, whichitself is in fluid communication with radial flow channel 265 thatconnects annular channel 260 to longitudinal flow channel 270. Workingfluid in longitudinal channel 270 is in fluid communication with innerlumen 115.

As shown in FIG. 3(b), fluid conduit 110 may extend through or otherwisecouple with an inner bore in distal seal insert 275 such that the innersurface of fluid conduit 110 and inner bore of distal seal insert 275form a substantially leakproof channel between inner lumen 115 andlongitudinal flow channel 270. Distal seal insert 275 is shown as beingsecured into place via a friction fit (e.g. press-fit) to create a seal.Distal seal insert 275 may be replaced by a functionally similar featuredirectly integrated into rotatable insert 215. Alternatively, distalseal insert 275 may include an outer annular channel (not shown) forhousing a sealing material, such as an o-ring, glue, caulking or othersuitable sealing material.

In an alternative example implementation, distal seal insert 275 can beomitted, such as when the torque cable 120 is impermeable to fluid flowand acts as both a torque cable 120 and fluid conduit 110.

FIGS. 3(a) and 3(b) illustrate the case where a central conductor 290 isconnected through ground tube 287 to the central conductor of connector315 (for example, an SMB connector). An outer conductor 285 may beconnected to ground tube 287, and connected to ground through the bodyof rotatable insert 215 (for example, by using set screw 246 to pressagainst conductor 285). Alternatively, if rotatable insert 215 is notelectrically conductive, conductors 285 and 290 can be electricallyconnected to electrical connector 315 via other suitable conductors orconductive means, such as soldering, use of conductive epoxy, laserwelding, and crimping.

In an alternative embodiment, in which it is important for theelectrical conductors to not be in electrical communication through theworking fluid, a proximal seal insert 277 shown in FIG. 3h may beprovided in order ensure that working fluid does not enter the region inwhich the conductors are separated and electrically routed. Such aproximal seal insert may include outer an annular channel for housing asealing material, such as an o-ring, glue, caulking or other suitablesealing material. Alternatively, a proximal seal insert may be press-fitinto place to create a seal, or the proximal seal insert may be replacedby a functionally similar feature directly integrated into rotatableinsert 215. The bore of the proximal insert may be sealed with a sealingmaterial or via tight tolerances between the bore and the activeconduit, such that fluid in longitudinal chamber 270 would not leakbeyond proximal insert within rotatable insert 115. As shown in theFigures, the active conduit may house a pair of electrical channels,such as a twisted pair or coaxial cable.

As noted above, annular channel 260 maintains fluid communicationbetween primary port 260 and radial channel 265 during rotation ofrotatable insert 215. In another embodiment, annular channel 260 may notbe present, such that radial channel 265 extends to an outer surface ofrotatable insert 215 and forms an aperture at a given angular position.Such an embodiment enables fluid communication between primary port 260and radial channel 265 when radial channel 265 is aligned with primaryport 260. This alignment may be achieved during an initial flushingoperation in which catheter 100 is pre-flushed prior to a procedure.Alternatively, the annular channel may be incorporated into outerhousing 210 rather than rotatable insert 215.

FIG. 3(b) further illustrates how working fluid within outer lumen 130is brought into fluid communication with chamber 240 in outer housing210 and secondary port 320 through flow path 209. An outer surface ofexternal sheath 105 is secured to an inner surface of outer housing 210,which may be at a distal portion of outer housing 210. For example, asshown in the Figure, outer housing 210 may include, at its distal end, astrain relief boot 250 to which external sheath 105 is secured (forexample, using an epoxy, UV glue, cyanoacrylate or other leak-tightadhesive). Strain relief boot 250 may include one or more deformablematerials such as rubber, silicone, polyurethane, other polymers orother suitable materials.

A portion of external sheath 105 is shown extending into outer housing210 such that outer lumen 130 is maintained and placed in fluidcommunication with chamber 240 through gap 255. Chamber 240 is shown asa small longitudinal section within outer housing, overlapping only asmall portion of secondary port 320. In other embodiments, chamber 240may extend over a larger longitudinal section, such that chamber 240overlaps with a larger portion. Gap 255 is maintained by coaxiallysecuring external sheath 105 and torque cable 120 to outer housing 210and rotatable insert 215, respectively. As described above, torque cable120 may be permeable to flow, thus enhancing fluid communication betweenouter lumen 130 and chamber 240.

FIG. 3(g) illustrates an embodiment in which active conduit 125 includesoptical fiber 417, which is routed through the central bore of distalseal insert 275 in a manner similar to that described above. Opticalfiber is connected to optical connector 317, which may be a standardoptical connector such as an angle polished connector. As noted above,an optical rotary joint may be provided within patient interface module536 for coupling light from a rotating optical fiber to a non-rotatingoptical fiber or optical element.

It is to be understood that the embodiments disclosed above are notlimited to a single active channel, and that two or more differentactive channels may be housed within torque cable 120. In otherembodiments, more than one electrical or optical active channel may beprovided. In one embodiment, one or more active channels may facilitatesignal delivery relating to imaging modalities, such as optical oracoustic imaging modalities. In other embodiments, one or more activechannels may provide power or actuating signals to other non-imagingactive elements located at a distal portion of catheter 100. Examples ofnon-imaging active elements include therapeutic treatment elements suchhigh intensity focused ultrasound transducers, laser ablation emitters,cryo-ablation and others.

FIG. 3(h) illustrates an embodiment in which active conduit 125 includesboth an optical channel and an electrical channel in active channel 419.Both optical fiber 417 and electrical conductors 285, 290 may be routedthrough the central bore of distal seal insert 275, and can be furtherrouted through to connect to their respective connectors as describedfor the single active channel embodiments.

In another embodiment, the secondary port may be located at a differentlongitudinal position than shown in FIGS. 1a , 3, 4 and 6. For example,secondary port 320 may be provided in a separate assembly that islocated remote from proximal connector 200, as shown in FIG. 1c . In yetanother embodiment, secondary port may be replaced by an opening inexternal sheath 105, where the opening is positioned at a longitudinallocation that is intended to lie within a subject, which may be employedfor flushing a cavity or lumen.

FIG. 4(a) shows a perspective view of proximal connector 200 thatcontains primary port 205 and secondary port 320. The proximal end ofexternal sheath 105 of catheter 100 is shown extending from the distalend of proximal connector 200.

FIG. 4(b) shows an exploded longitudinal cross-sectional view ofproximal connector 200. Abbreviated lengths of active conduit 125, fluidconduit 110, torque cable 120 and external sheath 105 are shown tosimplify the illustration of the construction of fluid rotary jointwithin proximal connector 200.

FIGS. 5(a)-(e) illustrate various embodiments whereby inner lumen 115 isbrought into fluid communication with outer lumen 130 at a distal end140 of catheter 100. Optional remote housing 400, which is mechanicallycoupled to torque cable 120 and fluid conduit 110, may support a remoteassembly, such as ultrasonic transducer 405 having active portion 410,shown as an example assembly in the Figures. Ultrasonic transducer 405is electrically contacted with signal 425 and ground 420 lines, whichare connected to coaxial cable 415 that is housed within torque cable120 and externally connected or connectable to a signal acquisitionsystem.

In the embodiment shown in FIG. 5(a), working fluid is delivered todistal end 140 of catheter through inner lumen 115, and passes overultrasonic transducer 405 before being returned to the proximal end ofcatheter 100 within outer lumen 130. Arrows 430 illustrate an exampledirection of flow, which may optionally be reversed, as described above.Such an embodiment can be beneficial in removing or reducing thepresence of bubbles on or near the surface of ultrasonic transducer 405,which can otherwise impede image quality and overall system performance.

During operation, torque cable 120, fluid conduit 110, remote housing400, and ultrasonic transducer 405 rotate under application of anexternal torque, thus enabling the scanning of a spatial zone externalto catheter 100. Scanning and longitudinal translation of the entirecatheter 100 or the rotating elements within the catheter thus enablethe collection of images over a range of intraluminal positions. Thedistal portion of external sheath 105 is formed from a material thatpermits substantial transmission of ultrasound waves through its walls.Nylon, Pebax, TPX, polyethylenes and several other compositions areexamples of materials that have such a property.

FIG. 5(b) illustrates another embodiment in which transducer 405 istiltably mounted on pivot 440, where an angular orientation oftransducer 405 is selected by varying a rotational speed of torque cable120. Such an embodiment, and related embodiments involving a fixedtransducer and a deflectable, movable, or pivotable member configured tovary an imaging angle of the transducer in response to changes in theangular velocity of the imaging assembly, are disclosed in US PatentPublication No. 20080177138 (titled “Scanning Mechanisms for ImagingProbe” and filed on Jan. 22, 2008) and US Patent Publication No.20090264768 (titled “Scanning Mechanisms for Imaging Probe” and filed onMar. 27, 2009), both of which are incorporated by reference in theirentirety. As further described in these patent publications, a restoringmechanism, such as a spring, may be included for biasing an orientationof the deflectable member in a given angular direction and/or towards apre-selected angular orientation. A mechanical stop may also be includedwithin the imaging assembly to limit the deflection angle of thedeflectable member.

As shown in FIG. 5(b), the flow provided by working fluid to transducer405 can be employed for exerting a torque, or restoring force, on thedeflectable transducer that influences the orientation of transducer405. FIG. 5(b) also shows how the flow path can be designed to directthe working fluid to effectively remove obstructions, such as airbubbles. It does this by directing flow to run parallel to desiredsurfacing, pushing the obstructions away. Fluid directing component 411directs the flow to run parallel to the bottom face of transducer 405,and then the distal dome portion of outer sheath 105 redirects the flowto run parallel to the top face of transducer 405. The obstructions onthe top face of transducer 405 impede the passage of acoustic waves, andair bubbles between transducer 405 and remote housing 400 create surfacetension that impedes the deflection of transducer 405. Other featuresmay be included to further direct flow to remove obstructions from keysurfaces.

For example, in some embodiments, there may be one or more straight orcurved flow passageways of various sizes and shapes to help direct flow.

FIGS. 5(c)-(e) show further embodiments in which remote housings 400 areconfigured to direct the flow of working fluid through channels 450 inremote housing 400. Channels 450 cause the working fluid to flow alongan underside of remote housing 400 and emerge at a longitudinal positionthat is distal to ultrasonic transducer 405. This ensures that theworking fluid does not directly impinge on ultrasonic transducer 405,thereby reducing a direct fluidic pressure applied to ultrasonictransducer 405 and having a lesser effect on its rotational dynamics andstability. Working fluid emerging from inner lumen 115 is redirected bywall 455 in remote housing, and electrical connections are made throughpassage 460, which is itself sealed and impervious to fluid flow. FIGS.5(d) and 5(e) show the lateral locations of pivot holes 470 positionedon opposite sides of remote housing in order to receive pivot pins 440.

In one embodiment, a conductive coiled spring 480 lies on either side ofthe housing and extends from the inner surface of remote housing 400 toa lateral surface of transducer 405. The conductive coiled springs 480may be insulated and may be connected via a straight extension of thespring material to either the signal connection 425 or ground connection420. Each spring 480 may electrically contact transducer 405 at alateral surface of the transducer, provided that each lateral surface oftransducer 405 is connected to the active portion of the transducer suchthat applying a voltage across the lateral surfaces of transducer 405results in a voltage being applied across the active portion oftransducer 405. This can be achieved, for example, by providing one ormore internal electrically conductive pathways within transducer 405 toachieve suitable electrical contact. Alternatively, contact pointsbetween electrically conductive pathways in the transducer and thesprings 480, other than the exemplary lateral surfaces can beincorporated into the transducer to achieve the same effect.

One area where bubbles may be undesired is at springs 480 as shown inFIG. 5(d), as the bubble surface tension may interfere with the propertwisting of the springs. Suitable channels or fluidic directingstructures may be provided to remove bubbles, or prevent the formationof bubbles, in or near springs 480.

FIG. 5(f) shows an embodiment of the distal portion of catheter 100where fluid flows in a proximal to distal direction through both outerlumen 130 and inner lumen 115. Working fluid may flow through a distalflush port 135 near the distal portion 140 of catheter 100. Thus, boththe inner lumen 115 and outer lumen 130 enable proximal to distal flow.The fluid may be provided to outer lumen in many ways. In oneembodiment, the working fluid is in fluid communication with outer lumen130 near fluid rotary joint 160. For example, distal seal 225 may bepartially permeable to flow. In such an embodiment, secondary port 320may not be required, or may functionally exist as port 135, as workingfluid delivered to outer lumen 130 is provided by primary port 205. Theamount of resistance to flow across distal seal 225 would determine therelative flow rates through the inner lumen relative to the outer lumen,with higher resistance across distal seal 225 causing higher flow ratesin the inner lumen relative to the outer lumen. Higher flow ratesthrough the inner lumen may provide more effective flushing of bubblesoff of the emitting surface of acoustic transducer 405, while higherflow rates through the outer lumen may minimize effects on transducertilting with embodiments similar to those in FIG. 5b . Alternatively,distal seal 225 can be omitted to enable flow through both the outerlumen and the inner lumen in the same direction.

While the flow of working fluid has been described, in the precedingembodiments, as flowing from primary port 205 to secondary port 320through inner lumen 115 and outer lumen 130, it is to be understood thatworking fluid may alternatively be flowed in an opposite configurationin which the working fluid returns along the inner lumen 115. Such analternative embodiment is illustrated in FIG. 5 g.

FIG. 5h shows an embodiment where the fluid rotary joint is used to coola mechanical rotary tool. The rotary tool 404 may be include tools forrotary ablation, such as a coronary atherectomy device including theRotoblator™ and other tools with abrasive burrs for mechanicaldislodging tissue under high rotational speed. Depending on therotational speed, the environment and the tissue being dislodged,significant heat can be generated. Tool 404 contains a network ofinternal channels 406 through which a cooling agent may be circulated toactively cool or heat the mechanical rotary tool. Since network 406 iskept isolated from the exterior of the probe, a number of cooling agentsmay be used with a reduced risk of damage from exposure to bodily fluidsand tissues including water, saline, gases such as nitrous oxide, andothers known in the art. Network 406 may be controllably formed usingmachining methods, injection molding, SLA, SLS, FDM, Polyjet, and othersknown in the art. Furthermore, network 406 may be a chaotic networkwithout predefined paths, such as those that may be present in porousmaterials such as ceramics, plastics, or metal foams.

FIG. 5i shows an example embodiment where the fluid rotary joint isinterfaced with a balloon catheter, such that an expandable volume ofthe balloon may be increased in response to a pressure within the innerlumen of the rotatable fluid conduit. In the example embodiment shown inFIG. 5i , an optical imaging assembly 407 is connected with, or inoptical communication with, optical fiber 417, and is supported withinremote housing 427. This imaging assembly may be used for opticalimaging using OCT, spectroscopy, angioscopy, and other optical imagingmodalities known in the art. The balloon 409, once inflated, may be usedto displace blood in a lumen to allow for adequate penetration ofimaging energy. Fluid or gas used to inflate the balloon flows throughthe fluid rotary joint (not shown) to a location remote from theproximal end of the catheter and through balloon access ports 416following example flow paths 430.

The optical imaging modality may be replaced by another imaging modalitysuch as ultrasound. The balloon may further be used to perform atherapeutic procedure that requires the use of a therapeutic agent. Forinstance, the use of refrigerants such as nitrous oxide, liquidnitrogen, or liquid helium with balloon catheters to performcryoablation of tissue has been described in the art. While thetherapeutic procedure is being performed, the imaging tool may be usedsimultaneously to monitor and/or guide the therapy.

Referring now to FIG. 6, a system diagram is provided showing the maincomponents of an example catheter-based system 500 employing a fluidrotary joint. System 500 includes imaging probe 544, which connects viapatient interface module 536 to image processing and display system 549.Image processing and display system 549 includes hardware to support oneor more imaging modalities, such as ultrasound, optical coherencetomography, angioscopy, infrared imaging, near infrared imaging, Ramanspectroscopy-based imaging, or fluorescence imaging. Specificembodiments of ultrasonic imaging probes and combined ultrasonic andoptical imaging probes are disclosed by Courtney et al. in US PatentPublication No. 20080177183, titled “Imaging Probe with CombinedUltrasounds and Optical Means of Imaging” and filed on Jan. 22, 2008, USPatent Publication No. 20080177138, titled “Scanning Mechanisms forImaging Probe” and filed on Jan. 22, 2008 and US Patent Publication No.20090264768, titled “Scanning Mechanisms for Imaging Probe” and filed onMar. 27, 2009, each of which are incorporated herein by reference intheir entirety.

Controller and processing unit 534 is employed to facilitate thecoordinated activity of the many functional units of the system, and maycontain some or all of the components shown in the Figure and listedherein. An operator interacts with image processing and display system549 via display and/or user interface 538. System 500 may furtherinclude electrode sensors 540 to acquire electrocardiogram signals fromthe body of the patient being imaged or treated. The electrocardiogramsignals may be used to time the acquisition of imaging data insituations where cardiac motion may have an impact on image quality. Theelectrocardiogram may also serve as a trigger for when to begin anacquisition sequence, such as when to begin changing the speed ofrotation of a motor in order to cause a desired scan pattern to takeeffect. For example, electrocardiogram triggered initiation of animaging sequence may enable images to be acquired during a particularphase of the cardiac cycle, such as systole or diastole.

Optical subsystem 530, if included in a particular implementation of animaging system, may include any or all of the following components:interferometer components, one or more optical reference arms, opticalmultiplexors, optical demultiplexers, light sources, photodetectors,spectrometers, polarization filters, polarization controllers, timingcircuitry, analog to digital converters, parallel processing arrays andother components for facilitating any of the optical imaging techniques.Ultrasound subsystem 532 may include any or all of the followingcomponents: pulse generators, electronic filters, analog to digitalconverters, parallel processing arrays, envelope detectors, amplifiersincluding time gain compensation amplifiers and other components forfacilitating acoustic imaging techniques.

Controller and processing units 534, if included in a particularimplementation of the imaging system, serve multiple purposes. Thoseskilled in the art will appreciate that specific components requireddepend on the needs of a particular type of imaging system. For example,controller and processing units may include any combination of a motordrive controller, data storage components (such as memory, hard drives,removable storage devices, readers and recorders for media such as CDs,DVDs, and Bluray™ discs), position sensing circuitry and/or software,angle detection circuitry and/or software, timing circuitry and/orsoftware, cardiac gating functionality, volumetric imaging processors,scan converters and others. As noted above, display and user interface538 is also optionally provided for either real time display or displayof data at a time later than the time at which imaging data is acquired.

It is to be understood that patient interface module 536 and controllerand processing units 534 are but one example illustration of theselection and organization of hardware subsystems, and that many otherimplementations are possible. For example, patient interface module 536may be housed with controller and processing units 534 within processingand display system 549.

Imaging catheter 100, as described above, includes a torque cablehousing a fluid conduit 110 that is connected to a fluid rotary joint200. Catheter 100 also houses active channel 546 that includes at leastone optical waveguide or a conductive path (for example, provided by twoconductive wires) that connect an emitter and/or receiver via connectionto an adapter, herein referred to as a patient interface module, orpatient interface module 536. Active channel 546 may include a fiberoptic, for example, wrapped by two layers of electrical wire that areelectrically insulated from one another. Active channel 546 may furtherbe reinforced by other structural features, such as helically wrappedwires or other designs used to construct imaging torque cables forrotating scan mechanisms.

Additional sensors may be incorporated as part of patient interfacemodule 536, such as position sensing circuitry, for example, to sensethe angle of rotation of a rotary component within the imaging probe 544and/or for detecting the angle of deflection of a member at the distalend 541 of the imaging probe 544. Imaging probe 544 may also include amemory component such as an EEPROM or other programmable memory devicethat includes information regarding the imaging probe to the rest of theimaging system. For example, it may include information regarding theidentification of specifications of the imaging probe 544 or may includecalibration information for the imaging probe 544. Additionally, patientinterface module 536 may include amplifiers to improve the transmissionof electrical signals or power between the imaging probe 544 and therest of the system.

The preceding embodiments have been illustrated using examples includingultrasonic and fiber optic imaging modalities, which can be readilyemployed for improved imaging systems for application such asintravascular ultrasound, optical coherence tomography, and intracardiacechocardiography, which employ rotary systems for scanning. However, itis to be understood that the systems and devices described herein arenot limited to such procedures, and can be employed in a wide variety ofdiagnostic and therapeutic procedures. Additional example proceduresinclude direct atherectomy, rotational atherectomy, laser ablation, andcombined visualization and treatment procedures, such as image guidedcryoblation, balloon angioplasty, and thrombectomy.

The aforementioned embodiments address a number of problems related tominimally invasive procedures involving scanning catheter systems. Inparticular, embodiments disclosed herein may support the miniaturizationof catheter systems that employ an internal fluid delivery lumen with aforward and return fluidic path.

It is to be understood that fill/purge rate of the catheter may beselected by selecting an appropriate size of the fluid conduit and innerlumen. Moreover, the present embodiments have demonstrated examples inwhich the design is adapted for both open and closed catheter systems.

Embodiments in which the inner lumen and outer lumen form a closed fluidpath eliminate the contact of biological fluids with the internalcomponents of the catheter, and mitigate the requirements for internalsterilization. A closed system also avoids the need for pre-filling,which is associated with problems such as absorption of water byplastics, freezing, sterility, corrosion issues, and additional weight.

Conversely, open systems involving a rotatable inner conduit (that has afluid lumen in fluid communication with a non-rotational external port),such as that in FIG. 5(f), enable the delivery of higher flush volumesin a smaller form factor, and may provide more flexibility in control offlow patterns within the catheter.

The working fluid can be employed for a wide variety of uses, includingproviding a medium for the coupling of imaging energy to and fromimaging devices, providing internal protection and/or cleaning ofinternal sensor surfaces (such as optical components and ultrasoundtransducers), heating and/or cooling, sterilization, providing a forcefor scanning systems involving rotatable components. As illustrated inFIG. 5, the geometry of the distal portion of the catheter may beconfigured for tailoring the flow profile within the distal portion ofthe catheter relative to sensitive or critical locations, enabling thepositioning of the active channels (e.g. fiber optic and/or electricalconductive channels) outside of the flush lumen. The diameter of thefluid conduit lumen may also be varied along its length, which can beuseful, for example, in controlling the local properties such as theflow rate, pressure on selected surfaces, flow profile, and/or otherproperties such as the Reynolds number.

In one embodiment, a catheter or medical probe with a rotary fluid jointas described above may be employed to control the temperature of theworking fluid and to expose the internal components of the catheter ormedical probe to different thermal environments. For example,controlling the temperature of the working fluid can support the warmingor cooling of an internal portion or device of the catheter or probe,and/or to warm or cool tissue surrounding catheter external sheath 105.In other non-limiting examples, the control of the working fluid can beemployed for the a change in the shape of a memory alloy (such anitinol) employed within catheter 100, and to cause a phase transitionof a material housed within catheter 100, such as gallium orgallium-based alloys such as galistan, that undergo phase transitions attemperatures close to body temperature.

In some cases, it might be desirable to use a gas rather than a liquidwithin a catheter. For example, gases may be used to make a portion ofthe catheter more buoyant, and help direct it within a fluid filledspace, such as the cardiovascular system. Furthermore, gases aregenerally less viscous than fluids, and may enable heat transport orinflation of balloon chambers along the length of the catheter morereadily than fluids.

In another embodiment, the fluid rotary joint may be employed as part ofa system that not only enables purging of air from the catheter, butalso enables varying the pressure within inner lumen 115 and outer lumen130. For example, after purging air out of the catheter using primaryport 205 as an infusion port and secondary port 320 as a venting port,it may then be possible to increase the pressure within the lumens ofthe catheter by effectively closing one of the two ports, such as usinga stopcock valve, clamp or a plug and applying pressure to the internallumens of the catheter via the other port. Alternatively, it may bepossible to decrease the pressure within the lumens of the catheter byeffectively closing one of the two ports, such as using a stopcockvalve, clamp or a plug and applying suction to the internal lumens ofthe catheter via the other port. A pressure gauge may be in fluidcommunication with the internal lumens of the catheter to measure theamount of pressure applied. Such pressure changes may inflate or deflateone or more balloons along the length of the catheter or actuate someother pressure-dependent mechanism.

Example embodiments provided above have been illustrated ascatheter-based systems, in which a fluid rotary joint is interfaced witha rotatable fluid conduit of a catheter. However, it is to be understoodthat a catheter is but one example of a medical probe that may beconfigured according to the present disclosure. For example, in otherexample implementations, a medical probe may include a rotatable fluidconduit that is housed within an insertable tube such as a cannula,trocar, and/or hypodermic needle, where the rotatable fluid conduit isinterfaced with a fluid rotary joint as described above.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

Therefore what is claimed is:
 1. A medical probe comprising: an externalsheath; a rotatable fluid conduit housed within said external sheath,said rotatable fluid conduit including an inner lumen; and a fluidrotary joint comprising: an outer housing including an external port,wherein a proximal portion of said external sheath is connected to adistal region of said outer housing; a rotatable insert having an innerchannel, wherein said rotatable insert is housed within said outerhousing and rotatable within said outer housing, and wherein a proximalportion of said rotatable fluid conduit is connected to said rotatableinsert, such that said inner channel is in fluid communication with saidinner lumen, and such that said rotatable fluid conduit rotates inunison with said rotatable insert; said external sheath defining anouter lumen, wherein said inner lumen is in fluid communication withsaid outer lumen at a location remote from a proximal portion of saidrotatable fluid conduit; a secondary port in fluid communication withsaid outer lumen, wherein said secondary port is located in a proximaldirection relative to a distal end of said rotatable fluid conduit, suchthat a direction of fluid flow in the outer lumen is opposite to adirection fluid flow in the inner lumen; and at least one seal betweensaid rotatable insert and an inner surface of said outer housing;wherein said inner channel is in fluid communication with said externalport under rotation of said rotatable fluid conduit; and wherein saidrotatable insert is connectable to a rotational drive mechanism.
 2. Themedical probe according to claim 1 wherein said rotatable insertcomprises a longitudinal channel; wherein said longitudinal channel isin fluid communication with said external port under rotation of saidrotatable insert; and wherein said proximal portion of said rotatablefluid conduit is received within said longitudinal channel.
 3. Themedical probe according to claim 2 wherein said rotatable insertcomprises a lateral channel, wherein said lateral channel is in fluidcommunication with said longitudinal channel, and wherein said lateralchannel is in fluid communication with said external port under rotationof said rotatable insert.
 4. The medical probe according to claim 3wherein said lateral channel is radially oriented.
 5. The medical probeaccording to claim 3 wherein an outer portion of said rotatable insertincludes an annular channel in fluid communication with said lateralchannel and said external port.
 6. The medical probe according to claim3 wherein an inner portion of said outer housing includes an annularchannel in fluid communication with said lateral channel and saidexternal port.
 7. The medical probe according to claim 1 wherein saidouter housing further includes said secondary port, and wherein saidouter lumen is in fluid communication with said secondary port.
 8. Themedical probe according to claim 7 wherein said external sheath isattached to an inner surface of said outer housing at a distal portionof said outer housing, such that said outer lumen is brought in fluidcommunication with a chamber within said outer housing, and wherein saidchamber is in fluid communication with said secondary port.
 9. Themedical probe according to claim 8 wherein said distal portion of saidouter housing includes a strain relief member attached to said externalsheath.
 10. The medical probe according to claim 1 wherein saidsecondary port is located near said proximal portion of said rotatablefluid conduit.
 11. The medical probe according to claim 1 wherein saidsecondary port is located at a position that is remote from saidproximal portion of said rotatable fluid conduit.
 12. The medical probeaccording to claim 1 wherein said rotatable fluid conduit is a torquecable.
 13. The medical probe according to claim 1 wherein said medicalprobe further comprises a rotatable shaft that houses said rotatablefluid conduit.
 14. The medical probe according to claim 13 wherein saidrotatable shaft is a torque cable.
 15. The medical probe according toclaim 1 further comprising: a remote assembly connected to a rotatableportion of said medical probe at a location remote from a proximal endof said rotatable fluid conduit; and an active channel to deliver poweror signals between said proximal end of said rotatable fluid conduit andsaid remote assembly.
 16. The medical probe according to claim 15wherein said rotatable insert includes a connector to interface aproximal end of said active channel with rotary adapter, wherein saidrotary adapter is configured to deliver external or signals from saidactive channel to an external non-rotary component.
 17. The medicalprobe according to claim 16 wherein said active channel includes twoelectrical conductors, and wherein said connector is a coaxialconnector.
 18. The medical probe according to claim 16 wherein saidactive channel is an optical fiber, and wherein said connector is afiber optic connector.
 19. The medical probe according to claim 16wherein said active channel is a first active channel and wherein saidconnector is a first connector, and wherein said medical probe furtherincludes: a second active channel and a second connector to interface aproximal end of said second active channel with said rotary adapter,wherein said rotary adapter is configured to deliver external or signalsfrom said second active channel to an external non-rotary component. 20.The medical probe according to claim 19 wherein said first activechannel includes two electrical conductors, and wherein said secondactive channel is an optical fiber.
 21. The medical probe according toclaim 15 wherein said remote assembly includes an imaging transducersupported by a remote housing, wherein said remote housing is attachedto a rotatable portion of said medical probe.
 22. The medical probeaccording to claim 21 wherein said remote housing is configured toredirect a flow of working fluid delivered from said inner lumen. 23.The medical probe according to claim 22 wherein said remote housing isconfigured such that flow of said working fluid is directed towards asurface of said imaging transducer.
 24. The medical probe according toclaim 22 wherein said remote housing is configured such that a flow ofsaid working fluid is initially directed to a region distal to saidimaging transducer.
 25. The medical probe according to claim 21 whereinsaid remote housing includes a flow redirecting feature to redirect aflow of working fluid.
 26. The medical probe according to claim 21wherein said remote assembly comprises a deflectable member to control adirection of imaging energy that is received with or emitted from saidimaging transducer.
 27. The medical probe according to claim 26 whereinsaid deflectable member is a pivotable member.
 28. The medical probeaccording to claim 27 wherein said pivotable member includes anultrasonic transducer.
 29. The medical probe according to claim 21wherein said imaging transducer is an ultrasonic transducer.
 30. Themedical probe according to claim 1 wherein said rotatable insert furthercomprises a proximal connector to connect said rotatable insert to saidrotational drive mechanism.
 31. The medical probe according to claim 1further comprising: a remote device connected to a rotatable portion ofsaid medical probe at a location remote from a proximal end of saidrotatable fluid conduit; wherein said remote device includes one or moreinternal flow channels in fluid communication with said inner lumen ofsaid rotatable fluid conduit; such that a temperature of said remotedevice may be controlled according to a temperature of a working fluiddelivered within said rotatable fluid conduit.
 32. The medical probeaccording to claim 31 wherein said remote device is an atherectomydevice.
 33. The medical probe according to claim 1 further comprising:an inflatable device connected to said medical probe at a locationremote from a proximal end of said rotatable fluid conduit; wherein saidinflatable device includes an expandable volume in fluid communicationwith said inner lumen of said rotatable fluid conduit, such that saidexpandable volume may be controlled by varying the pressure of a fluidwithin said inner lumen of said rotatable fluid conduit.
 34. The medicalprobe according to claim 1 wherein at least a portion of said rotatableconduit is impermeable to liquids.